Not applicable.
1. Technical Field
This invention relates to a milling tool for emptying the femoral medullary space, whilst creating a space for the shaft or shank of a hip prosthesis and a hip prosthesis suitable for insertion in said space.
The insertion of a hip prosthesis comprising a shaft and a ball to be attached at an angle thereto is a frequent, regularly relatively uncomplicated surgical operation.
However, difficulties arise in those cases in which the femoral medullary space to be emptied with the aid of a milling tool prior to the insertion of the hip prosthesis shaft is not straight, but instead curved, because then when using the conventional, straight milling tools regularly and in undesired manner bony substance to be maintained is also milled off.
2. Background Art
DE 29 14 455 discloses a device for producing a cavity in a bone for the insertion of an artificial joint part, in which two rasp halves adapted to the shape of the bone cavity to be produced are placed on a flexible turning tool drive shaft, the two rasp halves being movable against one another in the axial direction.
WO 94/27507 discloses a milling tool for emptying the femoral medullary space, whilst creating a space for the shaft of a hip prosthesis, having a flexible core and a plurality of conical, rotationally symmetrical milling segments, mounted in superimposed manner on the core and provided with central through-bores, which transfer or transmit a rotational force applied to the core. The pins provided therein for transferring the rotational force shear off, however, on bending the core in non-straight femoral medullary spaces.
The problem of the invention is to provide a milling tool making it possible to create a space for a hip prosthesis shaft following the path of the femoral medullary space, as well as a hip prosthesis, which can be inserted in such a non-straight, emptied femoral medullary space.
According to the invention this problem is solved by a milling tool for emptying the femoral medullary space, whilst creating a space for the shaft of a hip prosthesis, having a flexible core and a plurality of conical, rotationally symmetrical milling segments, mounted in superimposed manner on the core and provided with central through-bores, which transmit a rotational force applied to the core, and a device for tensioning the core. According to the invention the above-stated problem is also solved by having a hip prosthesis having a conically directed shaft and a ball mounted on the proximal end of the shaft, wherein the hip prosthesis comprises a flexible core, a plurality of conical, rotationally symmetrical segments, mounted in superimposed manner on the core and provided with a central through-bore and a device for tensioning the core bringing about a stiffening of the shaft formed from the individual segments.